1. Field of the Invention
The present invention relates to an optical lens system, and more particularly to a thin type optical lens system for taking image used in a mobile phone camera.
2. Description of the Prior Art
In recent years, with the popularity of mobile phone cameras, the optical lens system for taking image has become thinner and thinner, and the sensor of a general digital camera is none other than CCD (Charge Coupled Device) or CMOS (Complementary Metal Oxide Semiconductor). Due to advances in semiconductor manufacturing, the pixel size of sensors has been reduced continuously, and miniaturized optical lens systems for taking image have increasingly higher resolution. Therefore, there's increasing demand for image quality.
A conventional mobile phone camera's lens assembly usually consists of three lens elements: from the object side to the image side: a first lens element with positive refractive power, a second lens element with negative refractive power and a third lens element with positive refractive power, thus forming the so-called type of Triplet. To correct aberration, the optical lens system usually takes the form of “front aperture stop”. However, the arrangement of front aperture stop will increase stray light and also result in a relatively sensitive optical design.
The present invention mitigates and/or eliminates the afore-mentioned disadvantages.